Insect Antennae: Structure, Functions and Their Modifications

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1. INSECT ANTENNAE: STRUCTURE, FUNCTIONS AND MODIFICATIONS Created and Edited by :- Vikas Kumar Student of B.Sc (Agriculture)

2. 2 What is Antenna (Plural= Antennae) ? “Antennae are paired , freely mobile , segmented sensory appendages articulated with the head in front of or between the eyes . Antennae are also known as feelers .” These are well developed in adults and poorly developed in immature stages . Antennae are absent in order Protura and Class Arachnida while 2 pairs of antennae present in Class Crustacea .

3. 3 Structure of Antenna “Antennae are multi segmented and may be divided into 3 parts:- Scape :- It is the basal segment of a antenna, by which it is attached with the head . Pedicel :- It is the second segment of antenna which is shorter than scape . This segment having a sensory apparatus named ‘Johnston organ’. Flagellum :- It is the last segment of antenna which consists the remaining divisions of antenna and it greatly varies in its form and structure . It is also known as Clavola .

4. 4 Structure of Antenna

5. 5 Functions of Antennae The main function of antenna is sensory , which is modified according to habit and habitat of insect as given below:- Organs of smell :- Some insects have smell organs on their antennae by which they recognise their food . E.g. Ant, Honey Bee and Jiant moths .

6. 6 Organs of taste :- Some insects have taste hairs on their antennae by which they recognise the taste of their food . E.g. Cockroach . Stridulatorial organs :- Some insect bears sound producing organs in their antennae belonging order Orthroptera . e.g. Cricket .

7. 7 4. Chordotonal Organs :- Hearing organs ( Jhonston’s organ ) found in second segment ( pedicel ) of antenna. e.g. Male mosquito, Green bottle fly and Paper wasp etc. 5. Sexual Dimorphism :- Some insect belonging to the order Diptera and Hemiptera , having different type of Antenna in male and female, which help in sexual dimorphism . e.g. Male and Female Mosquito .

8. 8 Other Functions :- (a). Help the mandibles for holding the prey . (b). Useful for clasping the female during copulation . (c). Butterfly bears some transmitting and receiving organs in their antennae.

9. 9 Modifications of Antennae On the basis of shape and structure, the antennae may be following type:- Setaceous :- These are bristle like antennae, in which segments gradually decrease in size from base to apex and tappering into a point , presenting a whip like structure. e.g. Cockroach and Cricket .

10. 10 2. Filiform (Thread like ):- It is thread like antenna in which segments are uniform in thickness throughout from base to apex and never ends with bristle . e.g. Insect of order Orthroptera , Coleoptera namely Grasshopper and Ground Beetle .

11. 11 3. Moniliform (Like string of beads ):- Such type of antennae have globular or oval shaped segments with uniform thickness from base to apex , by which it looks like string of beads . It have constriction between the joints . e.g. Insect of order Isoptera namely Termite.

12. 12 4. Pectinate (Comb like ):- This is a comb like in structure in which each segment of the antenna possess long projection on one side , giving comb like appearance . e.g. Insect of order Lepidoptera namely Moth of Sugarcane root borer.

13. 13 5. Bipectinate (Double Comb like ):- In this type of antenna, each segment has the long projections on both side , giving double comb like appearance. e.g. Insect of order Lepidoptera namely Silk Moth.

14. 14 6. Serrate (Saw like ):- In this type of antenna, each segment is more or less triangular and projected on one side , which giving teeth of saw like appearance. e.g. Insect of order Coleoptera namely Pulse beetle.

15. 15 7. Flabellate (Feather like ):- In this type of antenna, in which projections of the flagellum become long and form a feather like structure , which is known as flabella . e.g. Insect of order Coleoptera namely Cedar Beetle.

16. 16 8. Plumose ( bursh like with dense hairs ):- In this type of antenna, each segment has the whorls of hairs arise from their joints and look like plumose. e.g. Insect of order Diptera namely Male Mosquito.

17. 17 9. Pilose ( bursh like with sparse hairs ):- In this type of antenna, each segment has the whorls of hairs arise from their joints like plumose but whorl contains less number of hairs . e.g. Insect of order Diptera namely Female Mosquito.

18. 18 10. Whorled :- Basically these are the setaceous , filiform or moniliform type of antennae in which each segment has a whorl of bristle at every joint . e.g. Insect of order Hemiptera namely Male of Mango Mealy Bug.

19. 19 11. Clavate (Clubbed ):- In this type of antenna, segments gradually increase in diameter towards the tip and last segment finally ending into a round core, look like club . e.g. Insect of order Lepidoptera namely Butterfly.

20. 20 12. Capitate (Clubbed with Knob ):- In this type of antenna, segments gradually increase in diameter towards the tip and suddenly last 3-5 segments enlarge to form a knob like structure. e.g. Red Rust Flour Beetle .

21. 21 13. Lamellate (Plate like ):- This is a modification of capitate antennae in which terminal segments extended on the side to form leaf like plate instead of forming the knob . e.g. Rhinoceros Beetle, Dung Rollers etc .

22. 22 14. Geniculate (Elbowed ):- In this type of antenna, the scape is greatly elongated , pedicel is short and flagellum is made up of small segments which make a bent on the scape look like knee . e.g. Ants, Honey Bee etc.

23. 23 15. Aristate (With arista ):- In this type of antenna, scape is smaller and broader , pedicel is longer than scape . The flagellum is longer than both and bears heavy bristle known as arista . e.g. House Fly .

24. 24 16. Stylate (With style ):- In this type of antenna, last segment of flagellum is modified into a long bristle known as style. e.g. Snipe fly, Robber fly.

25. 25 17. Fusiform :- In this type of antenna, scape is smaller and thin , while pedicle is larger and flagellum is modified into a hook like structure. e.g. Sphingid Moth.

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